There exists at present many types of mechanisms for opening windows. One such mechanism consists of a crank shaft mounted to the window pane and operable by means of a handle. Such handle, however, while being essential to the operation of the opening function, is a problem. Indeed, any type of interior decoration for a window is faced with the presence of such handles due principally to the space that it occupies on the interior side of the window. Curtains will be caught in the handles, which is a hinderance continuously met by users or by decoration professionals.